A Novel Evaluation Procedure for the Prediction and Assessment of Diffuser Humming in Steam Turbines

2018 ◽  
Author(s):  
Johannes Tusche ◽  
Christian Musch
Keyword(s):  
The Other ◽  
Evaluation Procedure ◽  
Steam Turbines ◽  
Test Rig ◽  
Basic Principles ◽  
Fluctuating Pressure ◽  
Low Pressure Turbine ◽  
Blade Row ◽  
Comprehensive Test ◽  
Last Stage

The mechanical integrity of turbine blade rows might be compromised by transient aerodynamic effects that occur in interaction with the diffuser. Effectively addressing this issue requires the prediction of the effects and the creation of a basis for their evaluation. This paper focuses on the specific case of diffuser humming in steam turbines. The paper describes the results obtained from two turbine diffusers with different pulsation frequencies calculated and tested under identical conditions. One diffuser forced a resonance of the last-stage blade row, while the other diffuser ensured the absence of resonance. The basic principles are described that allow estimating and quantifying the pulsation frequencies of the fluctuating pressure. To evaluate the developed approach comprehensive test runs were conducted using a Siemens low-pressure turbine test rig. These measured results are shown to provide validation of the calculation method.

Development of a Last Stage Blade Row Coupled by Damping Elements: Numerical Assessment of its Vibrational Behavior and its Experimental Validation During Spin Pit Measurements

2017 ◽  
Author(s):  
Christian Siewert ◽  
Frank Sieverding ◽  
William J. McDonald ◽  
Manish Kumar ◽  
James R. McCracken
Keyword(s):  
Structural Integrity ◽  
Mechanical Design ◽  
Vibration Response ◽  
Dynamic Loads ◽  
Steam Turbines ◽  
Response Level ◽  
Vibrational Behavior ◽  
Blade Row ◽  
Calculation Results ◽  
Last Stage

Last stage blade rows of modern low pressure steam turbines are subjected to high static and dynamic loads. The static loads are primarily caused by the centrifugal forces due to the steam turbine’s rotational speed. Dynamic loads can be caused by instationary steam forces, for example. A primary goal in the design of modern and robust blade rows is to prevent High Cycle Fatigue caused by dynamic loads due to synchronous or non-synchronous excitation mechanisms. Therefore, it is important for the mechanical design process to predict the blade row’s vibration response. The vibration response level of a blade row can be limited by means of a damping element coupling concept. Damping elements are loosely assembled into pockets attached to the airfoils. The improvement in the blade row’s structural integrity is the key aspect in the use of a damping element blade coupling concept. In this paper, the vibrational behavior of a last stage blade row with damping elements is analyzed numerically. The calculation results are compared to results obtained from spin pit measurements for this last stage blade row coupled by damping elements.

Sequential vs Multidisciplinary Coupled Optimization and Efficient Surrogate Modelling of a Last Stage and the Successive Axial Radial Diffuser in a Low Pressure Steam Turbine

2014 ◽  
Author(s):  
Kevin Cremanns ◽  
Dirk Roos ◽  
Arne Graßmann
Keyword(s):  
Steam Turbine ◽  
Design Process ◽  
Energy Demand ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Low Pressure ◽  
Steam Turbines ◽  
Low Pressure Turbine ◽  
Pressure Steam ◽  
Last Stage

In order to meet the requirements of rising energy demand, one goal in the design process of modern steam turbines is to achieve high efficiencies. A major gain in efficiency is expected from the optimization of the last stage and the subsequent diffuser of a low pressure turbine (LP). The aim of such optimization is to minimize the losses due to separations or inefficient blade or diffuser design. In the usual design process, as is state of the art in the industry, the last stage of the LP and the diffuser is designed and optimized sequentially. The potential physical coupling effects are not considered. Therefore the aim of this paper is to perform both a sequential and coupled optimization of a low pressure steam turbine followed by an axial radial diffuser and subsequently to compare results. In addition to the flow simulation, mechanical and modal analysis is also carried out in order to satisfy the constraints regarding the natural frequencies and stresses. This permits the use of a meta-model, which allows very time efficient three dimensional (3D) calculations to account for all flow field effects.

Vibration Investigation for Low Pressure Turbine Last Stage Blade Failure in Steam Turbines of a Power Plant

2012 ◽  
Author(s):  
Jyoti K. Sinha ◽  
W. Hahn ◽  
K. Elbhbah ◽  
G. Tasker ◽  
I. Ullah
Keyword(s):  
Power Generation ◽  
Power Plant ◽  
Steam Turbines ◽  
Cause Analysis ◽  
Low Pressure Turbine ◽  
Root Cause ◽  
Turbo Generator ◽  
Last Stage ◽  
Blade Failure

West Burton Power Plant, UK owned by EDF energy has 4 steam turbo-generator (TG) units for power generation. These units were installed and commissioned between 1967 and 1969 and have since operated smoothly without any major problems up to 2007. In 1995 and 1996, two TG sets, namely units 2 and 3, were retrofitted with the new design LP rotors and in 2005, retrofitting of HP rotor for all four TG units was commenced. The retrofitting was done without changing the foundation, but only with the aim to enhance the power output by 20MW (10 MW through LP retrofit and 10MW through HP retrofit). Cracking of the last stage blades of LP1 and LP2 turbine, steam-end blades has been observed in TG units 2 and 3 only. Hence the in-situ vibration measurements have been carried out on TG unit 3 and compared with healthy TG unit 1 to understand the dynamics of both units. This paper presents observations made on the dynamics of TG units 1 and 3, and results from the root cause analysis which may possibly lead to the solution to the blade failure problem in TG units 2 and 3.

Aerodynamic Optimization of the Nozzle for the Last Stage of Steam Turbine

2015 ◽  
Author(s):  
Aleš Macálka ◽  
Jaroslav Synáč ◽  
Jana Váchová ◽  
Miroslav Hajšman
Keyword(s):  
Design Process ◽  
Energy Demand ◽  
Cfd Simulation ◽  
Latin Hypercube Sampling ◽  
Optimized Design ◽  
Steam Turbines ◽  
Aerodynamic Optimization ◽  
Transient Time ◽  
Low Pressure Turbine ◽  
Last Stage

In order to meet the requirements of rising energy demand, one goal in the design process of modern steam turbines is to achieve high efficiencies. A major gain in efficiency is expected from the optimization of the last stage of a low pressure turbine (LP). This paper focuses on aerodynamic study by compound lean, axial sweep and hub end-wall of nozzle. The objective function is to maximize efficiency and minimize the leaving losses under the assumption of constant mass flow rate. The aerodynamic design process involves commercial 3D CFD tools. The maximization of the objective functions is achieved by means of a Design of Experiment (DoE) method “Optimal Space Filling” based on “Latin Hypercube Sampling”. Finally, the optimized design is analyzed by a transient (Time Transformation) CFD simulation. Furthermore, the detailed flow pattern of the optimized and the initial design is analyzed and compared.

Nuclear Steam Turbine With 60 inch Last Stage Blade

2013 ◽  
Author(s):  
Motonari Haraguchi ◽  
Tateki Nakamura ◽  
Hideo Yoda ◽  
Takeshi Kudo ◽  
Shigeki Senoo
Keyword(s):  
Steam Turbine ◽  
Nuclear Power ◽  
New Technologies ◽  
The Other ◽  
Power Equipment ◽  
Steam Turbines ◽  
Candu Reactors ◽  
Last Stage ◽  
Reactor Types ◽  
And Performance

Nuclear steam turbines can be classified into two categories, one for BWR reactors where some countermeasures are taken for radiated steam and water, the other is for PWR reactors and PHWR (CANDU) reactors where steam and water are not radiated. As for Low Pressure section, there is some difference in LP rotor end structure, and LP last three stage blade components can be applied to all reactor types. The trend in nuclear power equipment is in a direction of larger capacity. In response to this trend, longer last stage blade is required if same number of casing is kept to make nuclear turbines reasonably compact. This paper addresses some of the key developments and new technologies to be employed focusing on longer Last Stage Blade (LSB) development with Continuous Cover Blades (CCB), and other enhancements in product reliability and performance.

Survey of Twisted Blading Development in Steam Turbines

1969 ◽  
Vol 184 (1) ◽  
pp. 449-474 ◽  
Author(s):  
A. Smith
Keyword(s):  
Steam Turbine ◽  
Low Pressure ◽  
Scale Model ◽  
Steam Turbines ◽  
Power Station ◽  
Low Pressure Turbine ◽  
Last Stage ◽  
Turbine Blading

The development of steam turbine blading with high tip to hub diameter ratios over the last 50 years has been traced with particular emphasis on the reasons for adopting twisted blading in low pressure turbines. The aerodynamic concepts of the more generally accepted design bases for twisted blading are discussed and comparisons made between the efficiencies of selected twisted designs and straight blading. Current methods in the development of transonic low pressure blading for large 3000 rev/min central power station units are also described and the paper concludes by comparing the theoretical and measured steam angles across the last stage of a one-third scale model of a 136-in tip diameter low pressure turbine.

Development of Highly Efficient and Robust Ultra-Long Last Stage Blade for High Backpressure

2019 ◽  
Author(s):  
Ondrej Novak ◽  
Marek Bobcik ◽  
Vaclav Slama ◽  
Bartolomej Rudas ◽  
Josef Kellner ◽  
...  
Keyword(s):  
Natural Frequencies ◽  
Operating Conditions ◽  
Thermodynamic Efficiency ◽  
Steam Turbines ◽  
Supersonic Wind Tunnel ◽  
Low Pressure Turbine ◽  
Wide Range ◽  
Blade Shape ◽  
Last Stage ◽  
Very High

Abstract For modern steam turbines with large operating range and enhanced efficiency an ultra-long last stage rotor blade in a low pressure turbine part for high backpressure and 50 Hz fixed speed operation have been developed. An advanced design approach was used to create the blade shape with a high thermodynamic efficiency, high natural frequencies and a very high safety factor of average radial static stress in the blade span. Furthermore, the tip section of the bucket was improved to decrease a static tension and the hub section was refined to simplify the assembly. Tip and hub airfoils were experimentally validated in a supersonic wind tunnel. An advanced in-house procedure using numerical analysis to predict a potential danger of unstalled flutter was carried out for wide range of operating conditions.

scholarly journals CALIBRATION OF BTT MEASUREMENT WITH RESPECT TO SENSOR POSITION OVER SHROUDED LSB

2018 ◽  
Vol 20 ◽  
pp. 29-33
Author(s):  
Tereza Dadáková ◽  
Zdeněk Kubín
Keyword(s):  
Optical Sensors ◽  
Measurement Techniques ◽  
Fem Analysis ◽  
Strain Gauges ◽  
Steam Turbines ◽  
Test Rig ◽  
Sensor Position ◽  
Blade Tip ◽  
Last Stage ◽  
Efficiency And Reliability

In order to increase efficiency and reliability of steam turbines, last stage blades are equipped with mid-span tie-boss and shroud. We can use Blade Tip-Timing method (BTT) to measure vibration of shrouded blades, but the measured level of vibration is dependent on position of sensor over blade shroud. Hence, the results of BTT measurement have to be compared with other measurement techniques, like strain gauges, and with FEM analysis, to interpret these results right. This article provides findings we made on measurement of shrouded blades in test rig with eddy-current sensors, optical sensors and strain gauges at different positions of sensors over blade shroud. Measurement is also compared to FEM analysis.

scholarly journals Labels on the maps of the Third Military Survey of Austria-Hungary and on the survey maps of the Military Geographical Institute (Wojskowy Instytut Geograficzny) in Warsaw in the light of survey manuals

2015 ◽  
Vol 47 (1) ◽  
pp. 31-43 ◽  
Author(s):  
Wojciech Włoskowicz
Keyword(s):  
The Other ◽  
Standard Map ◽  
The Third ◽  
Last Stage ◽  
The Right ◽  
The Military ◽  
Topographic Surveys ◽  
The Way

Abstract Materials from topographic surveys had a serious impact on the labels on the maps that were based on these surveys. Collecting toponyms and information that were to be placed as labels on a final map, was an additional duty the survey officers were tasked with. Regulations concerning labels were included in survey manuals issued by the Austro-Hungarian Militärgeographisches Institut in Vienna and the Polish Wojskowy Instytut Geograficzny in Warsaw. The analyzed Austro-Hungarian regulations date from the years 1875, 1887, 1894, 1903 (2nd ed.). The oldest manual was issued during the Third Military Survey of Austria-Hungary (1:25,000) and regulated the way it was conducted (it is to be supposed that the issued manual was mainly a collection of regulations issued prior to the survey launch). The Third Survey was the basis for the 1:75,000 Spezialkarte map. The other manuals regulated the field revisions of the survey. The analyzed Polish manuals date from the years 1925, 1936, and 1937. The properties of the labels resulted from the military purpose of the maps. The geographical names’ function was to facilitate land navigation whereas other labels were meant to provide a military map user with information that could not be otherwise transmitted with standard map symbols. A concern for not overloading the maps with labels is to be observed in the manuals: a survey officer was supposed to conduct a preliminary generalization of geographical names. During a survey both an Austro-Hungarian and a Polish survey officer marked labels on a separate “label sheet”. The most important difference between the procedures in the two institutes was that in the last stage of work an Austro-Hungarian officer transferred the labels (that were to be placed on a printed map) from the “label sheet” to the hand-drawn survey map, which made a cartographer not responsible for placing them in the right places. In the case of the Polish institute the labels remained only on the “label sheets”.

Modeling of a Steam Turbine Including Partial Arc Admission for Use in a Process Simulation Software Environment

2011 ◽  
Author(s):  
Eric Liese
Keyword(s):  
Steam Turbine ◽  
Process Simulation ◽  
Process Model ◽  
Constant Pressure ◽  
Pressure Ratio ◽  
Simulation Software ◽  
State Variables ◽  
Steam Turbines ◽  
Software Environment ◽  
Last Stage

A dynamic process model of a steam turbine, including partial arc admission operation, is presented. Models were made for the first stage and last stage, with the middle stages presently assumed to have a constant pressure ratio and efficiency. A condenser model is also presented. The paper discusses the function and importance of the steam turbines entrance design and the first stage. The results for steam turbines with a partial arc entrance are shown, and compare well with experimental data available in the literature, in particular, the “valve loop” behavior as the steam flow rate is reduced. This is important to model correctly since it significantly influences the downstream state variables of the steam, and thus the characteristic of the entire steam turbine, e.g., state conditions at extractions, overall turbine flow, and condenser behavior. The importance of the last stage (the stage just upstream of the condenser) in determining the overall flowrate and exhaust conditions to the condenser is described and shown via results.

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